POLYPROPYLENE FIBERS - AN INDUSTRIALLY FEASIBLE PATHWAY TO HIGH TENACITY

Extensive studies concerning the spinning and drawing of polypropylene have resulted in the identification of an industrially feasible pathw ay for the production of fine (< 0.6 tex) very high tenacity fibres (8 5 cN/tex). Essentially, as-spun fibres are produced from a low molecul ar weight polymer (MFI 35 g/10min) extruded at 280 degrees C with a wi nding speed of 200 m/min. These paracrystalline fibres of low orientat ion are then subjected to a two-stage drawing process. The first stage , carried out at 60 degrees C, results in oriented paracrystalline fib res which are then, during the second stage, transformed at a temperat ure of 140 degrees C into highly oriented monoclinic fibres.